So called wire matrix printing apparatus is old and well known in the art. Such machines typically include one or more print heads, each head being provided with a plurality of printing elements, such as wires or pins, etc. Generally, the printing elements are grouped together to form a matrix such for example as four by five, five by seven or five by nine, etc., which, when energized, operate to form or print alphanumeric characters. The printing elements are selectively operable in various combinations to form the desired characters. In a typical printing system the selective operation is under the control of electromagnetic devices which in response to impulses generated by the analysis of a document or item by character generating apparatus are selectively actuated to determine or identify by their operation the combination of printing elements necessary to be moved from a print to a non-print position in order to form any particular desired alphanumeric character.
Prior to this invention, dot matrix printers, printing horizontal lines, typically used one pin and hammer arrangement for each vertical dot in a line, which results in a seven by five horizontal character being printed with a seven pin dot matrix printer. Such an arrangement typically places a high number of cycles and thus wear on the top row and the bottom row and also typically in the middle or fourth row. "E", which is the most common character, best displays this wear problem of the dot matrix printer. The top, middle, and bottom row require an excessively large number of impacts to print a single character while rows two, three, five and six require only a single dot each. Other common characters in the English alphabet both alpha and numeric show similar characteristics. To improve this condition, the present invention utilizes a nine vertical pin printer used in conjunction with a seven vertical dot matrix font. Then, on alternate sets, (sheets, pages, or job runs) a different pin set can be used.